So we had replaced the thermostat, coolant temp sensor, coolant hoses and even had the fans running manually as soon as start up. Even with all that as soon as we start the vehicle up within about 5-10 seconds the gauge shoots up past 260 as far it can go. The heater core is working because we had taken off the hoses and blew air thru them and coolant shot out. And we had already checked for any failed gaskets and we found none. Is there a part that corresponds to the temp gauge inside that would cause it to shoot up like that?